sigwaittest: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/bin/sigwaittest - from package: rt-tests

You may install the required package with command apt-get install {package}

Error in other languages:
sigwaittest: bevel nie gevind nie
sigwaittest: comandă negăsită
sigwaittest: comando não encontrado
sigwaittest: commande introuvable
sigwaittest: command not found
sigwaittest: käsku ei ole
sigwaittest: không tìm thấy lệnh
sigwaittest: komanda nerasta
sigwaittest: Kommando nicht gefunden.
sigwaittest: kommandot finns inte
sigwaittest: komut yok
sigwaittest: nie znaleziono polecenia
sigwaittest: níor aimsíodh an t-ordú
sigwaittest: no se encontró la orden
sigwaittest: no s'ha trobat l'ordre
sigwaittest: opdracht niet gevonden
sigwaittest: parancs nem található
sigwaittest: perintah tidak ditemukan
sigwaittest: príkaz nenájdený
sigwaittest: příkaz nenalezen
sigwaittest: команда не найдена
sigwaittest: командата не е открита
sigwaittest: 命令找不到
sigwaittest: コマンドが見つかりません